PDS APES 5th Period 2009-10

In class on Friday, we talked about Plate Tectonics and the Rock Cycle. For most of us, it was a throwback to middle school science, but there are some key points that are good to review:

Plate Tectonics:

• You can think of the earth like an egg. The shell, like earth’s crust, is the tough outside layer. Under the crust is the fluid mantle, like the white of an egg. This layer is constantly in motion. In the mantle, the magma approaches the hot core, rises, cools near the crust, sinks, and repeats this cycle. The innermost part of earth, like the yolk, is the core. The earth’s core is made of an inner and outer core. The outer core is still fluid, while the inner core is solid. The core is made up of mostly iron and nickel, which is the cause of the magnetic fields around earth.
• Earth is thought to be made up of about 12 tectonic plates.
• These plates float on the earth’s mantle, and subsequently move. Below is a picture of the tectonic plates that make up earth.
• 

http://www.countrywatch.com/imgs/global_thematic/Tectonic_Plates.gif

• These plates move in three different ways. First, they can diverge. This occurs when two plates spread apart from one another. Magma from the mantle comes up to fill the space between the plates and creates new crust as it cools. This forms mid-ocean ridges. The second type of movement is called convergence. When one plate becomes denser than the underlying mantle, it sinks back into the earth. This is called subduction. Subduction occurs at plate boundaries when the two plates collide. The third type of movement is on a transform fault. This process occurs when plates slide horizontally against each other. When this occurs along plate boundaries in the ocean, small earthquakes occur. However, when transformation occurs along fault lines under land, huge, destructive earthquakes can result.
• If you need more detail or clarification, refer to the handout given in class.

The Rock Cycle:

• The picture below depicts the rock cycle. It is pretty self-explanatory. 

http://mitchell.needham.k12.ma.us/technology/lessons/rocks/image/rock_cycle.jpg

• The three types of rock are: igneous, sedimentary, and metamorphic. Through processes of heating, cooling, melting, and squashing, the rocks change from one type to another.
• Also crucial to the process is weathering, which causes the breakdown of igneous and metamorphic rock and the creation of sedimentary.

If anyone has any questions or comments, feel free to ask!

Today in class, we learned more about water pollution. There is a list of the most common water pollutants in the book (pg 246, table 11-1), but it is important to note that the biggest water pollutant is sediment.

There are two categories of water pollution: point and nonpoint sources. According to our textbook, point sources are “single, identifiable sources that discharge pollutants into the environment.” Nonpoint sources are “large or dispersed land areas that discharge pollutants into the environment over a large area.” Here are the ways to clean up, prevent, or reduce pollution from each respective type of pollution.

Point Sources:

• Septic tanks-septic tanks are used to clean waste water when a sewage plant is not accessible (http://www.captainwater.com/septictank-picture.jpg)
  

  Here is an example of a septic system.

• Sewage Treatment-in cities and factories, waste water is pumped to a sewage treatment plant where it is cleaned and redistributed
• The Clean Water Act of 1972 regulates point source pollution. It regulates the discharge of pollutants into US waterways, it promotes water quality levels so citizens are able to fish and swim, and it requires discharge permits for effluent emissions (point sources). These are the key points of the Clean Water Act, but for more information, check out this site–> http://www.epa.gov/watertrain/cwa/

Nonpoint Sources:

• treat stormwater
• buffer zone vegetation along riverbanks (http://www.floatingwetlands.com/images/buffer-after.jpg)
  

  Here is an example of buffer zone vegetation. Note the low shrubs and grasses lining the banks of this wetland.

• reduce soil erosion-sand, silt, and clay in the water causes turbidity, a term used when particles block the ability of light to pass through a liquid
• retention ponds
• less organic fertilizer and pesticide use-these can potentially run into streams and lakes

I still don’t feel like I fully understand the coriolis effect. I know that the sun’s heat causes different pressures and winds, but I don’t really understand the significance. I think we mentioned that this effect is what creates biomes. Does it have an effect on anything else? Can someone explain it in a bit more detail for me?

Again, here is another good nutrient cycle story, by Ursula A., that may be helpful to review:

A Carbon Story
My name is Carbon. For the couple days or so I have been in the sky, stuck with my two twin brothers, Oxygen One and Oxygen Two. For now, I am relaxing and enjoying the heat of the sun, but many years ago I embarked on a crazy adventure all over the planet. Let me tell you about it.
So, years ago I was hanging around in the air, kind of like today, except it was extremely hot. My brothers (Oxygen One and Two) kept complaining about the heat, so I decided that we could take a swim. We diffused in the ocean, something a lot of carbon dioxide molecules like us do often. It was very refreshing. However, all of a sudden, we drifted into a huge growth of seaweed! We got all tangled in it and eventually entered the cells of the seaweed through its pores or stomata. As we entered the stomata with other carbon dioxide molecules, we became part of photosynthesis. Basically, we bonded with dihydrogen monoxide molecules (more commonly known as water) and became part of a huge glucose molecule! However, the glucose was quickly broken down for energy by the seaweed (a process called respiration) and I was all alone. I decided that I had had enough of swimming and diffused back into the air. I traveled through the air over the United States and entered the stomata of a small, dying dandelion. However, as this dandelion was frail and withering, we never got to respirate. I instead was stuck in the dying plant.
Weeks later, the plant was decomposing at a rapid rate. Decomposers like fungi and detrivitores like small insects were all over this little dandelion and the rotting leaves around it. The fungi broke down the carbon compounds (that’s me!) and then in the soil I stayed. I stayed there for millions of years, where I was compressed between layers of sedimentary rock. Slowly but surely the other carbon molecules and I were formed into what are called “fossil fuels.” One day I was just sitting around, like I had for the last million years when there was an extremely loud noise. I learned soon that humans were drilling for these deposits of fuels so that they could refine us into petroleum and other necessary products for their automobiles. Many refining plants later and I had been extracted and turned into petroleum…After sitting around for only a couple more days, a lady pumped me into her awesome, brand new Mercedes SLR and I was burned and let out as exhaust. It was back to the atmosphere for me, where I am waiting now for my next big adventure.

I think I asked this in class and either didn’t get an answer or didn’t listen to the answer. Why would a pull to a city be for the environmental advantages? Doesn’t a city just bulldoze over the environment to build skyscrapers and strip malls?

Looking over the study guide, I’m not sure I really understand the difference between artificial selection and genetic engineering. I know they are both used to create certain traits in organisms, but is one more effective than the other? Which is used more often, and does the type of species depend on which is the more frequently chosen method of controlling characteristics?

I was looking over Chapter 5 and realized that I don’t completely understand the “rain shadow effect.” I know how the rain dries and “sucks up the moisture” from plants, but where does this now moist rain go? And does this occur everywhere, or only near coasts? Is the rain shadow effect always a bad thing?

I just had a question about the NPP=GPP-R equation. The ecosystems with the highest NPP have more producers that are able to convert more solar energy to chemical energy faster. I don’t understand the R values though. Do the higher NPP ecosystems use less energy in respiration? If not, how are their NPP values so high?

SCIENTIFIC METHOD:

• our lab reports mimic the process because they lack background research
• our certainty in APES labs is limited by a lack of repetition and reproducibility, and by a lack of peer review

*also, for more on the full scientific method, here’s a diagram:

The Scientific Method

SO…WHAT CAN WE KNOW (be certain of)?

1) things we can disprove–we can’t always prove relationships and                                        absolute truths, but we can disprove them

2) whether the relationships are causal or correlated–either they are just                              able to be associated or one actually determines the other (http://stats.org/faq_vs.htm)

3) theory–lots of backup (experiments, repetition)

4) law–accurate descriptions of phenomena with lots of backup

*for a clarification of theory vs. law, here is a good website                                                                 http://www.wilstar.com/theories.htm

SO…HOW CAN WE KNOW?

• good experimental design–> controlled experiment (manipulating variables)–> observational experiments (just observing events occur and drawing reasonable conclusions)

I am still confused about the I=PAT equation. I don’t understand why affluence plays such a large part of the equation. Also, how can technology be a negative value, like it says in Watersheds? It would help me if we went over I=PAT and maybe did an example in class.